Why do some armed groups commit massive wartime rape, while others never do? Using an original dataset, I describe the substantial variation in rape by armed actors during recent civil wars and test a series of competing causal explanations. I find evidence that the recruitment mechanism is associated with the occurrence of wartime rape.Specifically, the findings support an argument about wartime rape as a method of socialization, in which armed groups that recruit by force— through abduction or pressganging—use rape to create unit cohesion. I examine observable implications of the argument, based on months of fieldwork, in case studies of the conflicts in Sierra Leone, El Salvador and Timor-Leste, and consider some of the longterm consequences of conflict-related mass rape. Speaker: Dara Kay Cohen, Assistant Professor of Public Policy, Harvard Kennedy School